My son works for Michigan Kenworth. He was checking my motor home and noticed a small leak on the inner right rear wheel seal. His boss said it was OK to replace it at the dealership on his time with their tools. (big jacks, 1" air tools , etc.) It's supposed to be a 1/2 hour job. Turned out to be seven hours which included parts chasing.
It is a Rockwell axel. Took the wheels off, pulled the axel and found the problem. There is a keeper on the bearing that has ears on it that have to be bent over to retain the bearing nut and the ears were broke and the tab that keeps the keeper centered on the axel broke too. Long story short, my wheels would have come off if my son had not paid attention to a small leak.
Total cost, $164.75 and a trip to Taco Bell at midnight. I'm a lucky man.